SAR interferometry with OTB

Dear all, Are there any documents or examples about SAR interferometry with OTB?

I am a researcher on SAR interferometry algorithms for over ten years and I am very excited to hear that OTB can do the job like ISCE or GAMMA etc. But I found it is hard to start as SAR interferometry is quite a long chain of algorithms to follow and the The configure files of diapOTB python scripts are not documented well. I believe someone has suceeded in SAR interferometry with OTB but the topic is seldom discussed here. Can someone kindly give me some advice?

Specifically:

  • In configure file ex_config_diapOTB_S1IW.json
	"in": 
	{
	    "Master_Image_Path": "image_1.tif",
	    "Slave_Image_Path": "image_2.tif",
	    "DEM_Path": "DEM.hgt"
	},

How to prepare the .tif and .hgt files?

Thanks for Reading and Best Regards.:slight_smile:

Hi,

I don’t know about interferometry, but I can help with DEM.

In OTB applications, the DEM path must be a directory that contains rasters. You can put your .hgt files in this directory. I believe that since OTB 5 or 6, other raster formats are also supported as DEM (e.g. GeoTiff, …).
Also, you can take a look to the DowloadSRTMTiles application that will automatically download the SRTM tiles for you!

Hope that helps,

Rémi

1 Like

Thanks for your reply Rémi!
But when I read the source code below to deal with the input hgt file, I think the “DEM.hgt” metioned above is not just a hgt file that downloaded with the DowloadSRTMTiles.

def getDEMInformation(dem):
    """
        Retrieve DEM information thanks to ReadImageInfo
    """
    # Get information about DEM (spacing, size ..)
    ReadDEMInfo = otb.Registry.CreateApplication("ReadImageInfo")
    ReadDEMInfo.SetParameterString("in", dem)
    ReadDEMInfo.SetParameterString("keywordlist", "true")
    ReadDEMInfo.Execute()

    dictDEMInformation = {}
    dictDEMInformation['spacingXDEM'] = ReadDEMInfo.GetParameterFloat("spacingx")
    dictDEMInformation['estimatedGroundSpacingXDEM'] = ReadDEMInfo.GetParameterFloat("estimatedgroundspacingx")
    dictDEMInformation['spacingYDEM'] = ReadDEMInfo.GetParameterFloat("spacingy")
    dictDEMInformation['estimatedGroundSpacingYDEM'] = ReadDEMInfo.GetParameterFloat("estimatedgroundspacingy")

    return dictDEMInformation

The keywords above such as “spacingx” were not metioned before, There must be a auxilliary file with it.

Thanks again!

Wei

Note that the DownloadSRTMTiles application is currently broken (see Broken links in DownloardSRTMTiles (#2164) · Issues · Main Repositories / otb · GitLab) because the download portal now require authentication to download the data.

1 Like

Yes, it is. I’ve downloaded the SRTM tiles manually. Thanks for your friendly reminder,julienosman.

The official site dimonstrated attrative pictures produced by DiapOTB.


But it is hard to follow.

Hello,

I can’t really help you on interferometry but you can have a look at the documentation of the diapotb module if you haven’t found it already. The doc is a bit light, but this page might help you.

Cédric

Thank you very much for your help, Cédric.
I have read the documentation already and it is really helpful to establish a general view of the DIapOTB. SAR interferometry is quite a long chain of algorithms to follow and preparations for the inputs are not mentioned there. I think examples might be more useful for a starter.

Best regards!

Wei